Publicising his imminent new series about the
evolution of animals, Sir David Attenborough said in an interview
this week that he thought a reduction in human population during
this century is impossible and “we’re lucky to be living when we
are, because things are going to get worse”. People will look back
in another 100 years “at a world that was less crowded, full of
natural wonders, and healthier”.

His is a common view and one I used to share. He longs for
people to enjoy the open spaces and abundant herds of game that he
has been fortunate enough to see. To that end he thinks it vital
that there should be fewer of us.

Ever so politely, I would now passionately disagree with the two
premises of his argument. It’s actually quite likely, rather than
impossible, that population will be falling by the end of this
century and it is also quite likely that the people alive then will
have lots more wilderness to explore and wildlife to admire than
today.

The rate at which world population grows has roughly halved from
more than 2 per cent a year in the 1960s to roughly 1 per cent a
year now. Even the total number of people added to the annual
population has been dropping for nearly 30 years. If those declines
continue, they will hit zero in about 2070 — not much more than 50
years from now. In recent decades the birth rate has fallen in
every part of the world. Fertility in Bangladesh has fallen from
nearly 7 children per woman in the 1960s to just over 2 today;
Kenya from 8 to 4.5; Brazil 5.7 to 1.8; Iran 6.8 to 1.9; Ireland
3.9 to 2.

It is still conventional wisdom that the only way to get
population growth down is to be nasty to people, albeit with noble
motives. You must coerce, bribe, shame or educate them into having
fewer babies against their preferences. One country — China — did
indeed bring down its birth rate with coercive measures in the
shape of a one-child policy. Another — India — tried to introduce
coerced sterilisation in the 1960s in return for food aid from
America, but was defeated by popular protest and democracy, factors
unknown in China.

Yet everywhere else voluntary birth control proved a more
effective weapon than coercion, and the birth rate came down just
as fast. This was because nice things happened: economic growth,
female emancipation and, above all, the conquest of child
mortality. So long as women have some access to the means of birth
control, then one of the best predictors of a falling birth rate is
a falling child mortality rate. Once children stop dying in
infancy, people plan smaller families. Once they think their kids
will survive, they start investing in them, rather than in having
more kids.

You can see this in the statistics. There is no country on Earth
with a child mortality rate below 10 per 1,000 births that has a
fertility higher than 3 children per woman; whereas all countries
except one (Swaziland) that have a child mortality rate above 100
also have a fertility rate above 4.5. Keep kids alive and you bring
down population growth.

Which is why the recent plummeting of child mortality in Africa
is such good news for Sir David and others with his concerns.
Thanks to rapid economic growth, better governance and much
improved public health, especially against malaria, most African
countries are now experiencing child-mortality falls of 5 per cent
or more a year, a rate that is far more rapid than it was in the
1990s. These falls will surely soon be followed, as night follows
day, by an even faster fall in birth rates.

Europe, Asia and Latin America have already gone through this
transition and most countries are producing babies at or below
replacement rate of 2.2 per woman, at which population stabilises
(without immigration). Africa, for so long written off as a special
(basket) case, is following suit almost exactly.

For this reason alone, I suspect the world population will stop
growing and begin to shrink even earlier than 2070 and almost
certainly within this century. But even if it does not, there is
good reason to reassure Sir David that our great grandchildren will
have more wildlife to look at than he has had. An ingenious study by scientists at Rockefeller
University in New York has recently calculated that even with
population continuing to grow, and even with people eating more
food and especially more meat, we have almost certainly already
passed “peak farmland”, because of the rate at which fertilisers
are improving yields. (Or we would have done if not for biofuels
projects.) We will feed nine or ten billion people in 2070 from a
considerably smaller acreage than we need to feed seven billion
today.

Land sparing is already occurring on a grand scale. Forest cover
is increasing in many parts of the world, from Scotland to
Bangladesh. Wildlife populations are booming in Europe (deer,
bears, boar, otters), in the polar regions (walrus, seals,
penguins, whales) and North America (turkeys, coyotes, bison,
geese) and this is happening fastest in the richest countries.
According to one recent report, animal populations grew by 6 per
cent in Europe, North America and Northern Asia between 1970 and
2012, while shrinking in tropical regions. There is almost a
perfect correlation between the severity of conservation problems
and poverty, because the richer people get, the less they try to
live off the land and compete with nature — the less they seek
bushmeat and charcoal from the forest.

Once again, Africa may spring a pleasant surprise. Over the past
four decades agricultural yields in Africa hardly budged while they
doubled or quadrupled in most of Asia. That is almost entirely down
to a dearth of fertiliser and it is beginning to change. If African
yields were to rise, the acreage devoted to farmland globally would
start to fall even faster, releasing more and more land for
“re-wilding”. The great herds and flocks that so delight Sir David
would reassemble in more and more places. The happy conclusion is
that making people better off and making nature better off are not
in opposition; they go hand in hand.